1. Field of the Invention
The present invention relates to an organic light-emitting display device and a method of fabricating the same, and more particularly, to an organic light-emitting display device capable of enhancing reflectivity and adhesion between a first electrode and a planarization layer.
2. Description of the Related Art
A conventional organic light-emitting display device includes a first electrode, an organic emission layer formed on the first electrode, and a second electrode formed on the organic emission layer. In the organic light-emitting display device, when a voltage is applied between the first electrode and the second electrode, holes are injected into the organic emission layer from the first electrode and electrons are injected into the organic emission layer from the second electrode. The holes and electrons injected into the organic emission layer are recombined in the organic emission layer to create excitons, which emit light when transitioning from an excited state to a ground state.
In the organic light-emitting display device, since the first electrode is a reflective type, i.e., formed to reflect light, and the second electrode is a transparent type, i.e., formed to transmit light, a top-emission organic light-emitting display device that emits light emitted from the organic emission layer toward the second electrode can be formed.
Here, while a conductive material having an excellent reflection property and an appropriate work function, is suitable for the reflective-type first electrode, it appears that there is no applicable single material satisfying the above properties at present.
Therefore, to satisfy the properties, the reflective type first electrode is formed in a multi-layer structure.
FIG. 1 is a schematic cross-sectional view illustrating a conventional method of fabricating an organic light-emitting display device including a reflective type first electrode.
Referring to FIG. 1, a reflective metal layer 11a is formed of aluminum or an aluminum alloy on a substrate 10, and then a transparent conductive layer 11b such as indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the reflective metal layer 11a. 
Then, a photoresist pattern is formed on the transparent conductive layer 11b, and the transparent conductive layer 11b and the reflective metal layer 11a are sequentially etched using the photoresist pattern as a mask. Accordingly, a first electrode 11 in which the reflective metal layer 11a and the transparent conductive layer 11b are sequentially stacked is formed. Thereafter, the photoresist pattern is removed using a strip solution.
Subsequently, the organic light-emitting display device is fabricated by forming an organic layer including at least an organic emission layer (not shown) on the first electrode 11 and by forming a second electrode (not shown) on the organic layer.
In the first electrode 11, the transparent conductive layer 11b has a high work function and is also transparent, and the reflective metal layer 11a formed of aluminum, etc., is a layer having an excellent reflection property. Therefore, the first electrode 11 may easily inject holes into the organic emission layer, and also efficiently reflect light emitted from the organic emission layer.
However, since a large difference generally exists between the work function of the reflective metal layer 11a formed of aluminum and the work function of the ITO layer 11b, there is a deterioration of interface properties between the layers, which results in deterioration of reflectivity between the layers.
Also, when the photoresist pattern is removed after the reflective metal layer 11a and the transparent conductive layer 11b are etched, the reflective metal layer 11a and the transparent conductive layer 11b are concurrently exposed to the strip solution, which may result in corrosion between the reflective metal layer 11a and the transparent conductive layer 11b due to a galvanic effect.
Accordingly, to prevent the reflective metal layer 11a and the transparent conductive layer 11b from being concurrently exposed to the strip solution, the reflective metal layer 11a is formed in an island pattern, which also requires another step of patterning the reflective metal layer 11a and the transparent conductive layer 11b. 